package com.leetcode;

import com.leetcode.common.ListNode;

/**
 * 141. 环形链表
 * 快慢指针(跟求链表中间节点的快慢指针不太一样)
 *
 * @author fy
 * @date 2022/4/11 19:02
 */
public class Solution141 {

//    public static class ListNode {
//        int val;
//        ListNode next;
//
//        ListNode(int x) {
//            val = x;
//            next = null;
//        }
//    }

    public boolean hasCycle(ListNode head) {
        if (head == null || head.next == null) {
            return false;
        }
        ListNode slow = head;
        ListNode fast = head.next;
        while (slow != fast) {
            if (fast == null || fast.next == null) {
                return false;
            }
            slow = slow.next;
            fast = fast.next.next;
        }
        return true;
    }

}
